The present invention relates to automated tire building machines and, more particularly, to methods and apparatus for precisely registering the longitudinal position of a movable tire building drum to the work stations of an automated tire building system.
It is well known that the components of most pneumatic tire constructions must be assembled in a way which promotes good tire uniformity in order to provide proper tire performance. For example, a tread which xe2x80x9csnakesxe2x80x9d as it goes around the tire circumference will cause wobbling as the tire is operated. For example, a carcass ply which is lopsided (longer cords on one side of the tire than the other side) can cause a variety of tire nonuniformity problems including static imbalance and radial force variations. For example, a tire which is not meridionally symmetric (e.g., tread not centered between beads) can cause a variety of tire nonuniformity problems including couple imbalance, lateral force variations, and conicity. Therefore, in order to meet typical tire performance requirements, the tire industry generally expends considerable effort in producing tires with good uniformity. Tire uniformity is generally considered to mean tire dimensions and mass distributions which are uniform and symmetric radially, laterally, circumferentially, and meridionally, thereby producing acceptable results for measurements of tire uniformity including static and dynamic balance, and also including radial force variation, lateral force variation, and tangential force variation as measured on tire uniformity machines which run the tire under load on a road wheel.
Although certain degrees of tire nonuniformity can be corrected in post-assembly manufacturing (e.g., by grinding), and/or in use (e.g., applying balance weights to the rim of a tire/wheel assembly), it is preferable (and generally more efficient) to build-in tire uniformity as much as possible. Typical tire building machines comprise a tire building drum around which the tire components are wrapped in successive layers including, for example, an innerliner, one or more carcass plies, optional sidewall stiffeners and bead area inserts (e.g., apex), sidewalls, and bead wire rings (beads). After this layering, the carcass ply ends are wrapped around the beads, the tires are blown up into a toroidal shape, and the tread/belt package is applied. Typically the tire building drum is in a fixed location on the plant floor, and the various layers of components are applied manually or automatically using tooling registered to reference points on the fixed drum in order to ensure component placement with the desired degree of precision. The tooling is generally fixed relative to the tire building drum, for example a guide wheel on an arm extending from the same frame (machine base) which supports the tire building drum.
The present invention addresses the unique problems of alignment and registration which arise when the tire building drum is no longer fixed, but instead is a work-piece in a flexible manufacturing system (FMS) wherein the building drum is moved between automated work stations for application of successive component layers in successive work stations. The context of the present invention is an FMS having work-pieces (tire building drums) which are too large to allow the use of a precision pallet conveyor, so the tire building drums are moved (propelled) by other means which are not necessarily able, by themselves, to achieve sufficient accuracy in positioning the tire building drums relative to the work stations. The work stations each have a centerline, or xe2x80x9cworking axisxe2x80x9d of the work station tire assembly devices (tools). Thus, one problem to be addressed is to precisely align the axis of the tire building drum with the working axis in each work station. Such alignment includes assuring that each point along the entire drum length of the tire building drum axis of revolution is within a specified precision distance of the work station working axis, i.e., alignment comprises making the tire building drum axis of revolution coincident with the work station working axis. A second problem, related to the first, is to precisely register the longitudinal position of the tire building drum relative to each work station. A solution to both problems provides three dimensional positioning of the tire building drum relative to the tools and devices of each work station with the desired degree of precision.
U.S. Pat. No. 4,314,864 (Loeffler, et al; 1982) discloses a method and apparatus for building a tire wherein a tire assembly drum (11) is mounted by means of a drum support (15) on a longitudinally movable carriage (12) which moves on a guideway (20) past a plurality of operation stations (A-G) spaced longitudinally along the guideway. Under control of an operator, the carriage/drum is moved to each station in succession, first to last, for successive tire assembly operations. Mechanical datum (30), fixedly located at each operation station, are provided to engage mechanical locators (31) secured to the carriage, and a bladder (42) is provided selectively to cause engagement of the locators with the mechanical datum at each successive station to locate the tire assembly drum precisely with respect to the operation station. After operations at the last operation station, the carriage is returned to the first operation station. The carriage is attached to an operator""s platform (16) with which it moves longitudinally, propelled by a drive system (22) which moves the operator""s platform. The carriage is individually supported on wheels (19) that ride along individual tracks, or rails (20) that form the guideway. Similarly, wheels (21) are provided under the operator""s platform which roll along the ground powered by the drive system. An operator is normally positioned on the operator""s platform with ready access to power and sequencing panels and controls. The carriage wheels and rails appear similar in construction to railroad rails and flanged wheels. The platform is controlled to stop the carriage at the various operation stations and does so with relative accuracy. Precise positioning is obtained by use of mechanical locators on the carriage which, upon lowering of the carriage by means of the bladder, interfit with a mechanical datum fixed at each operation station. The mechanical datum comprises preferably at least three frustroconical dogs (30) anchored in the floor. The mechanical locators comprise orienting plates 31 secured to the frame of the carriage, each having an aperture (33) the periphery of which is conically tapered to mate with one of the frustroconical dogs. In order to permit the carriage to move independent of the platform as it comes to rest in positive alignment upon the dogs, a tapered pin (45) and bracket (53) are used to attach the carriage to the platform. The tapered pin is mounted vertically on the carriage and has a long shank of reduced diameter. The bracket is mounted on the operator""s platform and has a vertical tapered bore which matingly engages a conical portion of the tapered pin such that when the carriage is lowered onto the dogs, the tapered pin lowers, moving the reduced diameter shank into the bore of the bracket, thereby allowing relative movement between the pin and bracket, and therefore between the carriage and platform. A limitation of the disclosed tire building apparatus/method is that there is only one tire assembly drum being used to assemble only one tire at a time in all the operation stations, using them in sequence and then reversing direction to return to the first station to begin the next tire. Also, precision location involves sliding of surfaces between the dogs and orienting plates, thereby inducing wear and subsequent loss of precision necessitating part replacement for maintenance.
U.S. Pat. No. 1,309,894 (Kilborn; 1919; assigned to Goodyear), discloses an early form of tire assembly automation wherein a number of carcass-mounting units (5, FIG. 1) are arranged in a linear xe2x80x9calignedxe2x80x9d series, and a treading/stitching machine (12) rides on a trackway (7) for intermittent correlation with each of the carcass-supporting units of the series. Referring to FIG. 4, the trackway is seen to comprise a pair of flat-topped rails (23, 24) upon which ride wheels (22, 18) which have flanges (28, 26) to hold the wheels on the rails similar to conventional railroad rails and wheels. There are two front wheels (22) and two rear wheels (18). The treading/stitching machine can be rolled off the rails to ride on the floor by means of an extra flange (28) on the front wheels sized to allow the machine to roll about on the wheel flanges. The machine is xe2x80x9creadily pushed into a centered position before any of the tires, its weight serving to maintain it stationary during the stitching of any of the tire treads . . .xe2x80x9d upon the trackway by a human operator, who uses a pointer (58, FIG. 3) to center the machine relative to a tire carcass: xe2x80x9cThe operator has but to mark the center of a tire carcass and arrange the machine with the pointer (58) in alignment with the mark on the tire.xe2x80x9d
The present invention is intended to overcome the limitations of the prior art by providing method and apparatus for precision positioning in three dimensions of tire building drums moving through automated tire building systems.
According to the invention, a method for positioning each of three or more movable tire building drums at each of three or more work stations of an automated tire building system as the tire building drums move longitudinally forward along a working axis extending through the three or more work stations, comprises the steps of: providing a work station longitudinal reference point at each of the three or more work stations; providing a drum reference point upon each of the three or more movable tire building drums; moving each of the tire building drums longitudinally forward into one of the three or more work stations; stopping each of the tire building drums within its respective work station after the drum reference point moves longitudinally forward past the work station longitudinal reference point; and moving each tire building drum longitudinally rearward until the drum reference point abuts against the work station longitudinal reference point to precisely position each of the tire building drums longitudinally within its respective work station.
According to the invention, the method further comprises the steps of: providing the work station longitudinal reference point of each of the three or more work stations upon a surface of an intake server located at each of the three or more work stations for operating the tire building drums; and providing the drum reference point of each of the three or more movable tire building drums upon a surface of each of the three or more movable tire building drums. Even further, the method comprises the step of: moving the three or more intake servers at each of the work stations from a normally retracted position outward across the working axis into a position to couple the intake servers to the tire building drums located at the work stations; and using the intake servers for moving the tire building drums longitudinally rearward until the drum reference point abuts against the work station longitudinal reference point.
According to the invention, the method further comprises the steps of: independently moving each tire building drum with a self-propelled vehicle; and flexibly connecting each tire building drum to one of the vehicles with a coupling which can be uncoupled. Preferably each tire building drum is moved longitudinally rearward by the steps of: coupling the work station to the tire building drum; uncoupling the tire building drum from the vehicle; and longitudinally moving the tire building drum relative to the vehicle. Preferably, the rearward moving means is used to hold the drum reference point against the work station longitudinal reference point. Preferably, the tire building drums are coupled to vehicles with a flexible connecting means which allows controlled lateral and vertical movement of the tire building drum relative to the vehicle while the vehicle is moving the tire building drum.
According to the invention, apparatus for positioning each of three or more movable tire building drums at each of three or more work stations of an automated tire building system as the tire building drums move longitudinally forward along a working axis extending through the three or more work stations, comprises: a work station longitudinal reference point at each of the three or more work stations; a drum reference point upon each of the three or more movable tire building drums; means for moving each of the tire building drums longitudinally forward into one of the three or more work stations; means for stopping each of the tire building drums within its respective work station after the drum reference point moves longitudinally forward past the work station longitudinal reference point; and means for moving each tire building drum longitudinally rearward until the drum reference point abuts against the work station longitudinal reference point to precisely position each of the tire building drums longitudinally within its respective work station.
According to the invention, the apparatus further comprises: an intake server means located at each of the three or more work stations for operating the tire building drums; a surface of the intake server means having thereupon the work station longitudinal reference point of each of the three or more work stations; and a surface of each of the three or more movable tire building drums having thereupon the drum reference point of each of the three or more movable tire building drums. Furthermore, the apparatus comprises: means for moving the three or more intake server means at each of the work stations from a normally retracted position outward across the working axis into a position to couple the intake server means to the tire building drums located at the work stations; and means for using the intake server means for moving the tire building drums longitudinally rearward until the drum reference point abuts against the work station longitudinal reference point.
According to the invention, the apparatus further comprises: means for independently moving forward each tire building drum; and means for flexibly connecting each tire building drum to a respective one of the forward moving means with a coupling which can be uncoupled. Furthermore, the apparatus comprises: means for coupling the work station to the tire building drum; means for uncoupling the tire building drum from the respective one of the forward moving means; and means for longitudinally moving the tire building drum relative to the respective one of the forward moving means. Preferably, the apparatus comprises means for holding the drum reference point against the work station longitudinal reference point. Preferably, the flexible connecting means allows controlled lateral and vertical movement of the tire building drum relative to the respective one of the forward moving means.
According to the invention, an apparatus for longitudinal registration of a movable tire building drum to an automated tire building system work station, wherein the automated tire building system comprises one or more work stations, and a plurality of tire building drums wherein each tire building drum is independently moved longitudinally forward into and out of each work station, comprises: an intake server located at the work station for meshing with and operating the movable tire building drum; a work station longitudinal reference point upon a forward facing surface of the intake server; a drum reference point upon a rearward-facing surface of the movable tire building drum; means for laterally extending the intake server rearward of the tire building drum; a flexible connection flexibly attached to the tire building drum, having a cam follower on a free end of the flexible connection; an intake actuator arm rotatably attached to the intake server; a box cam slot in the intake actuator arm for coupling with the can follower; and means for rotating the intake actuator arm after coupling with the cam follower for moving the tire building drum longitudinally rearward to abut the drum reference point against the work station longitudinal reference point.
According to the invention, the flexible connection further comprises: a coupling arm rotatably connected between the tire building drum and the cam follower; a crank arm rotatably connected between the coupling arm and the independent forward moving means such that the crank arm rotatably connects to a portion of the coupling arm located between the cam follower and the tire building drum connection. Even further, a self-propelled vehicle provides the independent forward moving means for the tire building drum; and the flexible connection is attached to the vehicle such that it has a closed position which couples the tire building drum to the vehicle for independently moving the tire building drum forward, and has an open position which uncouples the tire building drum from the vehicle to allow the tire building drum to be longitudinally moved relative to the vehicle. The flexible connection may further comprise: a stop arm and height adjustment screw positioned to counteract a vertical force component of a forward moving force imposed by the vehicle when the flexible connection is closed; and dimensions and angles such that forward moving force imposed on the flexible connection when it is closed also causes the flexible connection to remain closed. Furthermore, length for the box cam slot is provided to allow coupling with the cam follower when the vehicle halts at a specified range of different longitudinal positions within the work station. Furthermore, clearance between the crank arm and a bracket rotatably connecting the crank arm to the vehicle is provided to allow controlled lateral movement of the tire building drum relative to the vehicle.
The present invention is particularly useful in conjunction with a system for simultaneously building a plurality of tire carcasses, such as is disclosed in the aforementioned U.S. Patent Application Ser. No. 09/957,785 entitled METHOD FOR MANUFACTURING TIRES ON A FLEXIBLE Manufacturing SYSTEM. The method disclosed therein generally comprises the tire building steps of establishing a sequence of at least three and up to ten work stations; advancing at least three disconnected tire building drums along a working axis extending through the at least three work stations; and applying one or more tire components to the tire building drums at each of the work stations. Then the resulting green tire carcass is removed at the last of the work stations. Finally, the tire building drum is advanced from the last work station after the green carcass has been removed to the first work station. The tire building drums are each independently advanced along the working axis. Each of the disconnected tire building drums are advanced along the working axis so that the axis of rotation of the disconnected tire building drums is aligned with the working axis. The plurality of disconnected (i.e., independently movable, not connected to one another) tire building drums can be substantially simultaneously advanced along a working axis with self propelled devices to which the tire building drums are mounted from one work station to another. The tire building drums are advanced along the working axis so that an axis of rotation through the building drum is maintained at a constant predetermined height and location and in parallel alignment with the working axis. An intake server is located at each of the work stations for operating the tire building drums. The intake servers are coupled to the building drums while maintaining the axis of rotation through the building drums at the constant predetermined height and location and in parallel alignment with the working axis. The intake server at each of the work stations move from their normally retracted position outward across the working axis into a position to couple to that tire build drum. Then the building drums are uncoupled from the is intake servers after the tire component(s) have been applied to the building drums. Next, the intake server at each of the work stations are retracted to their normally retracted position, prior to the now uncoupled tire building drum advancing to the next work station. The step of applying one or more tire components to the tire building drums at each of the work stations includes applying the tire components to the tire building drums while maintaining the axis of rotation through the building drums at the constant predetermined height and location and in parallel alignment with the working axis. This is accomplished by providing one or more application drums at each of the work stations for applying the tire component(s) to the building drums. The application drums are moved from their normal retracted position away from the working axis to a location where the tire components can be applied to the building drums while maintaining the axis of rotation through the building drums at the constant predetermined height and location and in parallel alignment with the working axis. Then the application drums are retracted at each of the work stations to their normally retracted position, prior to advancing the tire building drum to the next work station.
Other objects, features and advantages of the invention will become apparent in light of the following description thereof.